16 month old biting and pinching

My 16 month old has started biting, i tell him a firm “no” and “keep your mouth to yourself” he just smiles at me 😂xx

My family is a little more physical if a “no” doesn’t work. My nephew started doing this. If he didn’t respond to “no” then he would get a little pop on the mouth or hand. Nothing hard but just enough to surprise him and not to hurt him. He very quickly decided he didn’t like that a stopped the behavior.